Riding lawn mower with friction drive

ABSTRACT

A riding lawn mower may include a cutting deck coupled to a cutting blade, an engine, a deck drive coupled to the engine to receive power for operating the cutting blade, a ground drive coupled to the engine to receive power for movement of the riding lawn mower over ground, and a friction drive coupling the deck drive to the engine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International ApplicationPCT/US2010/038831, filed Jun. 16, 2010, the contents of which areincorporated herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to vehicles, and in particular, tovehicles configured for lawn maintenance including mowing.

BACKGROUND

Grass is commonly maintained with lawn care machinery such as, forexample, lawn mowers, lawn tractors, and/or the like. Walk-behind lawnmowers are often compact and inexpensive, and are usually configuredwith comparatively small engines of less than about 200 cubiccentimeters (cc). At the other end of the spectrum, ride-on lawntractors can be quite large, have engine sizes generally exceeding 400cc, and can be configured with various functional accessories (e.g.,trailers, tillers, and/or the like) in addition to grass cuttingcomponents. Riding lawn mowers often fall in the middle, providing theconvenience of a riding vehicle as well as a typically larger cuttingdeck as compared to a walk-behind lawn mower.

However, prior riding lawn mowers have been unable to overcome variousdifficulties. For example, certain prior lawn mowers have requiredlarge, expensive engines in order to obtain sufficient operative powerto carry a rider and/or to drive a desired size of cutting deck. Otherriding lawn mowers have been expensive, having prices similar to pricesof lawn tractors. Yet other riding lawn mowers have been undesirablylarge when boxed or otherwise configured for transportation and/or sale,limiting the types of vehicles that may be used to transport the lawnmower to a desired location (for example, from a retail store to thehome of a purchaser).

SUMMARY

This disclosure relates to systems and methods for riding lawn mowersand components thereof. In an exemplary embodiment, a riding lawn mowercomprises a cutting deck coupled to a cutting blade, and an internalcombustion engine having a displacement of less than 225 cubiccentimeters. The internal combustion engine is coupled to the cuttingblade via a friction drive.

In another exemplary embodiment, a drivetrain for a riding lawn mowercomprises a friction wheel, and an engine flywheel coupled to a deckdrive. The engine flywheel is frictionally engageable with the frictionwheel, and the flywheel comprises a neutral bearing centrally locatedthereon. The drivetrain further comprises a differential comprising atleast one plastic gear. The differential is coupled to the frictionwheel in order to transfer power to at least one drive wheel of theriding lawn mower.

The contents of this summary section are provided only as a simplifiedintroduction to the disclosure, and are not intended to be used to limitthe scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the following description, appended claims, andaccompanying drawings:

FIG. 1A illustrates an exemplary riding lawn mower in accordance with anexemplary embodiment;

FIG. 1B illustrates a block diagram of components of an exemplary ridinglawn mower in accordance with an exemplary embodiment;

FIG. 1C illustrates configuration of an engine with respect to anexemplary riding lawn mower in accordance with an exemplary embodiment;

FIG. 2 illustrates an exemplary riding lawn mower frame in accordancewith an exemplary embodiment;

FIG. 3A illustrates a neutral bearing system for a friction drive inaccordance with an exemplary embodiment;

FIG. 3B illustrates a friction wheel for a friction drive accordancewith an exemplary embodiment;

FIG. 4 illustrates a drivetrain for a riding lawn mower including afriction drive in accordance with an exemplary embodiment;

FIG. 5A illustrates an exploded view of a differential for a riding lawnmower in accordance with an exemplary embodiment;

FIG. 5B illustrates an assembled view of a differential for a ridinglawn mower in accordance with an exemplary embodiment;

FIG. 6A illustrates an exploded view of a dual pulley and brake systemfor a deck drive of a riding lawn mower in accordance with an exemplaryembodiment;

FIG. 6B illustrates an assembled view of a dual pulley and brake systemfor a deck drive of a riding lawn mower in accordance with an exemplaryembodiment;

FIG. 7 illustrates a deflector for a riding lawn mower in accordancewith an exemplary embodiment;

FIGS. 8A and 8B illustrate a foot rest for a riding lawn mower inaccordance with an exemplary embodiment; and

FIG. 9 illustrates a seat for a riding lawn mower in accordance with anexemplary embodiment.

DETAILED DESCRIPTION

The following description is of various exemplary embodiments only, andis not intended to limit the scope, applicability or configuration ofthe present disclosure in any way. Rather, the following description isintended to provide a convenient illustration for implementing variousembodiments including the best mode. As will become apparent, variouschanges may be made in the function and arrangement of the elementsdescribed in these embodiments, without departing from the scope of theappended claims. For example, the steps recited in any of the method orprocess descriptions may be executed in any order and are notnecessarily limited to the order presented. Moreover, many of themanufacturing functions or steps may be outsourced to or performed byone or more third parties. Furthermore, any reference to singularincludes plural embodiments, and any reference to more than onecomponent or step may include a singular embodiment or step. Also, anyreference to attached, fixed, connected or the like may includepermanent, removable, temporary, partial, full and/or any other possibleattachment option. As used herein, the terms “coupled,” “coupling,” orany other variation thereof, are intended to cover a physicalconnection, an electrical connection, a magnetic connection, an opticalconnection, a communicative connection, a functional connection, and/orany other connection.

For the sake of brevity, conventional techniques for mechanical systemconstruction, management, operation, measurement, optimization, and/orcontrol, as well as conventional techniques for mechanical powertransfer, modulation, control, and/or use, may not be described indetail herein. Furthermore, the connecting lines shown in variousfigures contained herein are intended to represent exemplary functionalrelationships and/or physical couplings between various elements. Itshould be noted that many alternative or additional functionalrelationships or physical connections may be present in a practicallight riding vehicle, for example a riding lawn mower.

Principles of the present disclosure reduce and/or eliminate problemswith prior riding lawn mowers. For example, various riding lawn mowersconfigured in accordance with principles of the present disclosure areconfigured to utilize smaller and/or less expensive engines, for exampleengines having displacement of up to 224 cc. Other riding lawn mowersconfigured in accordance with principles of the present disclosure areconfigured to be smaller and/or lighter than certain prior riding lawnmowers in order to, for example, be able to fit in certain commonpassenger vehicles (e.g., minivan, sport utility vehicle, light truck,and/or the like) when boxed for retail sale. For example, an exemplaryriding lawn mower configured in accordance with principles of thepresent disclosure is configured with a dry, unboxed weight of about 87kilograms and a wheelbase of about 112 centimeters. Yet other ridinglawn mowers configured in accordance with principles of the presentdisclosure are configured to be manufacturable at a reduced expense ascompared to certain prior riding lawn mowers.

In various exemplary embodiments, a riding lawn mower is configured witha friction drive. As used herein, a “friction drive” generally refers toa powertrain where power is transferred from the engine to at least oneother operational component of the powertrain via frictional engagementof two parts (for example, a flywheel and a friction wheel perpendicularto one another), rather than solely via a conventional drive shaft andgearset.

In various exemplary embodiments, with reference to FIG. 1A, riding lawnmower 100 comprises a steerable powered vehicle configured with variouscomponents for mowing a lawn. For example, riding lawn mower 100comprises frame 110 coupled to a cutting deck 184 having at least onecorresponding cutting blade. Moreover, riding lawn mower 100 may beconfigured with any suitable components configured to allow an operatorto mow grass, for example a deflector 180, a footrest 182, a seat 186,and/or the like.

With reference now to FIG. 1B, in various exemplary embodiments, ridinglawn mower 100 further comprises engine 130 coupled to friction wheel140. Engine 130 is coupled to friction wheel 140 via a flywheel 134 andneutral bearing system 136. Friction wheel 140 is coupled todifferential 150, for example, via one or more of driveshafts, pinions,chains, and/or the like, in order to transfer power to differential 150.Differential 150 transfers operational power to ground drive 160Flywheel 134 is also coupled to deck drive 170 via, for example, one ormore of belts, pulleys, driveshafts, pinions, chains, and/or the like.

In various exemplary embodiments, engine 130 comprises an internalcombustion engine, for example an internal combustion engine fueled bygasoline, diesel fuel, ethanol, and/or any other suitable fuel. Engine130 may be configured with a displacement from about 175 cc to about 224cc. Engine 130 may comprise an engine typically utilized for awalk-behind lawn mower. In one exemplary embodiment, engine 130comprises a Briggs and Stratton model W14 engine having a displacementof about 190 cc. Moreover, engine 130 may comprise any engine configuredto provide sufficient power to enable suitable operation of riding lawnmower 100 (e.g., partial or full operation of the ground drive andpartial or full operation of the deck drive while supporting the weightof an operator).

In various exemplary embodiments, with momentary reference to FIG. 1C,engine 130 may be configured with respect to the other components ofriding lawn mower 100 so as to achieve a desired configuration of thecenter of gravity of engine 130. For example, engine 130 may be coupledto riding lawn mower 100 such that the center of gravity of engine 130is located “ahead” (e.g., closer to the front of riding lawn mower 100)of the rear axle of riding lawn mower 100. Moreover, engine 130 may alsobe coupled to riding lawn mower 100 such that the center of gravity ofengine 130 is located “behind” (e.g., closer to the rear of riding lawnmower 100) the front axle of riding lawn mower 100 and/or the center ofgravity of riding lawn mower 100. In this manner, engine 130 may belocated so as to reduce and/or minimize mechanical components couplingengine 130 to ground drive 160 and/or deck drive 170, for example byeliminating a belt coupling engine 130 to ground drive 160.

With reference now to FIGS. 1A and 2, in various exemplary embodiments,riding lawn mower 100 is configured with a frame 110 (e.g., frame 210).In an exemplary embodiment, frame 210 is configured with a pair oftubular structures (a “dual-tubular” frame). Frame 210 is configured toprovide structural support to riding lawn mower 100. Frame 210 maycomprise one or more of steel, aluminum, titanium, iron, and/or othersuitable metals and/or alloys thereof. In an exemplary embodiment, frame210 comprises HSLA 50 A-10 1102 hot rolled steel tubing having an outerdiameter of between about 3.0 centimeters to about 3.5 centimeters.Moreover, frame 210 may further comprise various plates, brackets,flanges, fasteners, and/or the like, as suitable, in order to couple toand/or support other components of riding lawn mower 100.

In an exemplary embodiment, frame 210 is configured with a dual-tubulardesign in order to provide flexion within frame 210, responsive toriding lawn mower 100 passing over uneven ground. The spacing betweentubes comprising frame 210 may be suitably varied, as desired, in orderto obtain a desired rigidity and/or other mechanical characteristics offrame 210.

In various exemplary embodiments, frame 210 is configured with one ormore curved portions 210A. In this manner, frame 210 may be configuredto at least partially “flex” or bend in a suitable direction (e.g., in avertical direction), responsive to an applied force. By varying the bendradius of curved portions 210A, the dimensions of frame 210 (e.g., theouter diameter, the inner diameter, the wall thickness, etc.), placementof various coupling brackets 212, and the like, frame 210 may beconfigured to flex in a desired manner. For example, frame 210 isconfigured to flex in a manner such that riding lawn mower 100 respondsto an applied force as if riding lawn mower 100 were configured with aconventional shock absorber system (e.g., springs, struts, linkages,and/or the like). In this exemplary embodiment, frame 210 is configuredto provide the equivalent of about 2 centimeters (2 cm) of suspensiontravel. In other exemplary embodiments, frame 210 is configured toprovide the equivalent of between about 1 cm and about 10 cm ofsuspension travel. In this manner, riding lawn mower 100 may beconfigured with an improved level of comfort for an operator, forexample by reducing shock transferred to the rider. Moreover, byproviding a suspension-like function, frame 210 may reduce wear onand/or damage to other components of riding lawn mower 100.

Frame 210 may be monolithic. Alternatively, frame 210 may comprisemultiple components coupled together. Moreover, frame 210 may be cast,pressed, sintered, die-cut, machined, stamped, bonded, laminated,polished, smoothed, bent, rolled, molded, plated, coated, and/orotherwise shaped and/or formed via any suitable method and/or apparatus.

In various exemplary embodiments, with reference now to FIGS. 1B and 3A,engine 130 is mounted to frame 210. Engine 130 is coupled to frictionwheel 140 via a flywheel 134 configured with a neutral bearing system136 (e.g., neutral bearing system 336). In an exemplary embodiment,neutral bearing system 336 comprises a bearing 337 and a cover plate338. Cover plate 338 may be configured with a flange 339 extending atleast partially into bearing 337 in order to couple thereto.

In an exemplary embodiment, flywheel 134 is coupled to engine 130 (forexample, coupled to the crankshaft of engine 130) via a fastenerdisposed through a cavity generally located in the center of flywheel134. Bearing 337 may be disposed in the cavity. In an exemplaryembodiment, an outer surface of bearing 337 is coupled to flywheel 134(e.g., via frictional engagement). An inner surface of bearing 337 iscoupled to cover plate 338 (e.g., via frictional engagement). In thismanner, flywheel 134 may be coupled to engine 130 in order to facilitateoperation of the friction drive, while maintaining a suitably continuoussurface across which friction wheel 340 may traverse during operation ofthe friction drive.

In an exemplary embodiment, bearing 337 comprises a needle bearing. Inanother exemplary embodiment, bearing 337 comprises a roller bearing. Inyet other exemplary embodiments, bearing 337 comprises a ball bearing.Moreover, bearing 337 may comprise any suitable components and/ormechanisms configured to allow cover plate 338 to remain fixed withrespect to friction wheel 340 when cover plate 340 is engaged byfriction ring 341, while flywheel 134 is permitted to rotate.

In various exemplary embodiments, flywheel 134 comprises steel. In otherexemplary embodiments, flywheel 134 comprises powdered metal. In theseembodiments, flywheel 134 may be infused with copper or other suitablematerial in order to provide desirable frictional and/or structuralcharacteristics of flywheel 134. In an exemplary embodiment, flywheel134 comprises a material having a hardness exceeding that of aluminum,for example a hardness in excess of 60 HRb on the Rockwell B scale.Moreover, flywheel 134 may comprise any suitable material configured tofrictionally engage with friction wheel 340 in order to transfer forceto other components of riding lawn mower 100. Flywheel 134 may beconfigured to be suitable for use over a variety of operating RPM rangesof engine 130, for example from about 0 RPM up to about 4000 RPM.

In various exemplary embodiments, with reference now to FIGS. 3B and 4,friction wheel 140 (e.g., friction wheel 340) is configured tofrictionally engage with flywheel 134. Friction wheel 340 comprisesfriction ring 341 coupled to wheel body 342. Wheel body 342 isconfigured to provide structural support to friction wheel 340.Moreover, wheel body 342 is configured to couple to other power transfercomponents (e.g., a driveshaft), in order to transfer force received viafriction ring 341. In an exemplary embodiment, wheel body 342 couples toa driveshaft via a suitably shaped cavity 343 in order to transferrotational force.

Friction ring 341 may comprise any suitable material configured tofrictionally engage flywheel 134. In an exemplary embodiment, frictionring 341 comprises rubber. In another exemplary embodiment, frictionring 341 comprises a composite. Friction ring 341 may be removed fromwheel body 342 and replaced with a new ring, as suitable, for exampleresponsive to wear.

In various exemplary embodiments, riding lawn mower 100 is configured toreduce flat spotting on friction ring 341. As used herein, “flatspotting” generally refers to wearing of a non-round area on frictionring 341 caused by flywheel 134 continuing to rotate when friction wheel340 is frictionally coupled to flywheel 134 close to or at the center offlywheel 134. In this position (“neutral”), friction wheel 340 does nottransfer rotary motion from flywheel 134, but simply suffers frictionalwear at the exterior (e.g., on friction ring 341). The resulting wearand consequent “out of roundness” of friction ring 341 reduces theeffectiveness of later frictional engagement between friction wheel 340and flywheel 134. For example, as the flat spot on friction ring 341passes over flywheel 134, slippage can occur, leading to undesirablelagging, surging, and/or otherwise uneven power delivery.

In order to reduce flat spotting, various prior approaches for frictiondrives have disengaged a friction wheel and a flywheel in the neutralposition and/or positions close thereto. In contrast, in variousexemplary embodiments, flywheel 134 and friction ring 341 remain infrictional engagement in the neutral position. Flat spotting of frictionring 341 is prevented because, at the neutral position, friction ring341 is in contact with cover plate 338 which is rotatably supported bybearing 337. Thus, cover plate 338 remains fixed with respect tofriction ring 341, while flywheel 134 continues to rotate, eliminatingflat spotting of friction ring 341. Instead of rotational wear onfriction ring 341, rotational movement of hearing 337 occurs. In thismanner, prolonged life of friction ring 341 may be achieved. Moreover,riding lawn mower 100 may thus be configured with smoother, morereliable power transfer between engine 130 and other components ofriding lawn mower 100.

In an exemplary embodiment, when friction wheel 340 is displaced acrossflywheel 134 in a first direction out from the center of flywheel 134,riding lawn mower 100 is operative in a “forward” direction. Conversely,when friction wheel 340 is displaced across flywheel 134 in a seconddirection (opposite the first direction) out from the center of flywheel134, riding lawn mower 100 is operative in a “reverse” direction. Invarious exemplary embodiments, the mechanical components configured todisplace friction wheel 340 in the reverse direction simultaneouslyoperate a “reverse” direction indicator, for example via a lever armclosing an electrical contact. In this manner, an operator may benotified of “reverse” operation each time riding lawn mower 100 entersoperation in the reverse direction.

Once power is transferred from engine 130 to friction wheel 340, it maythen be delivered to other components of riding lawn mower 100, forexample to a differential 150. With reference now to FIGS. 1B, 5A, and5B, in an exemplary embodiment, a differential 150 (e.g., differential550) comprises a plurality of gears (e.g., one or more of ring gears,planet gears, side gears, and/or the like). One or more gears comprisingdifferential 550 may comprise plastic or other suitable structuralmaterial, for example in order to reduce one or more of noise, weight,cost, and/or the like.

In an exemplary embodiment, differential 550 comprises at least onedifferential shaft 552. Differential shaft 552 may comprise any suitablestructural material configured to transfer torque, for example, steel,aluminum, titanium, iron, and/or the like. In an exemplary embodiment,differential shaft 552 comprises elevated temperature drawing (“ETD”)150 steel. Differential shaft 552 may be monolithic. Differential shaft552 may also comprise multiple portions. Moreover, portions ofdifferential shaft 552 may coupled to one another in any suitablemanner. In an exemplary embodiment, portions of differential shaft 552are coupled to one another via a dowel pin. In this manner, the portionsof differential shaft 552 may be aligned with respect to one another, asdesired.

In an exemplary embodiment, differential 550 is coupled to the rearwheels of riding lawn mower 100, for example via a drive gear associatedwith each rear wheel. The drive gear for each rear wheel may compriseany suitable material and/or be configured with any suitable diameterand/or tooth pattern, as desired. In an exemplary embodiment, the drivegear for each rear wheel comprises plastic. In other exemplaryembodiments, the drive gear for each rear wheel comprises glass-fillednylon, for example nylon filled with from about 20% to about 40% glass.

Turning now to FIGS. 1B, 6A and 6B, in various exemplary embodiments,riding lawn mower 100 is configured as a “single belt” system. Statedanother way, riding lawn mower 100 is configured with one belt couplingengine 130 to deck drive 170, but no other belts. In various priorriding lawn mowers and/or lawn tractors, a “dual belt” system isutilized, where one belt couples the engine and the deck drive, andanother belt couples the engine and the ground drive. In contrast, asingle-belt system in accordance with principles of the presentdisclosure allows for reduced complexity and reduced manufacturingexpense.

In various exemplary embodiments, riding lawn mower 100 is configured asa “dual pulley” system. Stated another way, riding lawn mower 100 isconfigured with two pulleys for adjusting tension on a belt couplingengine 130 and deck drive 170. In various prior riding lawn mowersand/or lawn tractors, a “single pulley” system is utilized. In contrast,a dual-pulley system in accordance with principles of the presentdisclosure allows for greater geometric advantage when varying thetension on an associated belt.

In an exemplary embodiment, a deck drive 170 (e.g., deck drive 600)comprises a belt 610 routed about pulleys 610 and 620. Pulleys 610and/or 620 may be spring-loaded or otherwise configured to impart adesired tension to belt 610, for example responsive to operation of aclutch. Belt 610 transfers force to deck pulley 640 which is coupled toa cutting blade configured to cut grass. As the clutch is engaged,pulleys 620 and 630 move, taking up slack in belt 610 and thus graduallyengaging belt 610 against pulleys 620, 630, and 640 in order to turn acutting blade coupled to pulley 640. As the clutch is released, pulleys620 and 630 move in an opposite direction, reducing tension in belt 610and thus at least partially disengaging belt 610 from pulleys 620, 630,and 640. Thus, force is no longer delivered to the cutting blade, andthe cutting blade eventually ceases rotation.

In various exemplary embodiments, pulleys 620 and 630 are configuredwith an extended height in order to allow for greater verticaldisplacement of pulley 640 and/or other components of deck drive 600. Inan exemplary embodiment, pulleys 620 and 630 are configured with aheight at least twice the height of belt 610, providing additional roomfor belt 610 to move with respect to pulleys 620 and 630. In thismanner, deck drive 600 can accommodate increased vertical displacementas compared to deck drives lacking pulleys with extended heights.

In order to reduce the likelihood of injury, it is desirable for acutting blade to more rapidly come to a stop when a clutch isdisengaged. Thus, in various exemplary embodiments, riding lawn mower100 is configured with a linked clutch and brake system. Continuing withreference to FIGS. 6A and 6B, one or more structural components 650(e.g., brackets, linkages, couplers, and/or the like) are coupled topulleys 620 and/or 630. Structural components 650 may further be coupledto various braking components (e.g., components configured to impart adrag force to a cutting blade, a wheel, a pulley, and/or the like, suchas a brake caliper, a brake disk, etc). In this manner, in theseexemplary embodiments, disengagement of the clutch simultaneouslyactivates braking components, bringing the cutting blade to a stop morerapidly.

With reference now to FIG. 7, in various exemplary embodiments, ridinglawn mower 100 is configured with a deflector 700. Deflector 700 isconfigured to at least partially guide, contain, and/or control materialejected from the cutting deck of riding lawn mower 100. For example,deflector 700 may be configured with various suitable angles, lengths,curvatures, and/or the like, in order to achieve a desired pattern ofgrass clippings ejected from the cutting deck.

In an exemplary embodiment, deflector 700 is configured with a loop 720configured to allow an operator to grasp it. In this manner, deflector700 may be moved, raised, lowered, and/or otherwise adjusted, forexample in order to vary the path of debris ejected from the cuttingdeck or to remove an obstruction, without an operator (or with minimal)needing to reach underneath deflector 700 to grasp it. In this manner,deflector loop 720 allows an operator to move deflector 700 withoutexposing the operator to the debris path beneath deflector 700.

In an exemplary embodiment, deflector loop 720 is a loop. In otherexemplary embodiments, deflector loop 720 may comprise a flange, a knob,a rod, a handle, and/or the like, or other suitable component configuredto allow an operator to move deflector 700 without exposure to a debrispath.

Turning now to FIGS. 8A-8B, in various exemplary embodiments, ridinglawn mower 100 is configured with a footrest 800. Footrest 800 iscoupled to frame 210. Footrest 800 may comprise any suitable structuralmaterial, for example plastic, metal, composite, and/or the like. In anexemplary embodiment, footrest 800 comprises glass-filled polypropylenein an amount from about 15% glass to about 40% glass. In variousexemplary embodiments, footrest 800 is configured with edges 800A and800B cantilevered away from frame 210. Edges 800A and 800B may becantilevered any suitable distance (e.g., about 15 centimeters), whilestill remaining strong enough to support the weight of an operator ofriding lawn mower 100, for example an operator weighing about 100kilograms. In various exemplary embodiments, footrest 800 is configuredwith inserts 810. Inserts 810 may provide cushioning and/or grip for thefeet of an operator, as desired.

With reference now to FIG. 9, in various exemplary embodiments, ridinglawn mower 100 is configured with a seat 900. Scat 900 is configured toaccommodate an operator. In an exemplary embodiment, seat 900 comprisescalcium filled polypropylene, for example from about 20% to about 30%calcium. In another exemplary embodiment, seat 900 comprises VistaMaxx™brand polypropylene based elastomers manufactured by ExxonMobilChemical.

In various exemplary embodiments, seat 900 is configured with a gaschamber about the exterior of seat 900. In this manner, seat 900 may beconfigured with suitable structural characteristics and/or manufacturingcharacteristics, for example ease of molding. Moreover, seat 900 may beconfigured with various padding components, for example snap-in paddingcomponents 910A and 910B. Scat 900 may be coupled to frame 210 and/orother portions of riding lawn mower 100, as suitable.

In an exemplary embodiment, riding lawn mower 100 is configured with afoot-operated bypass. Stated generally, a “bypass” refers to componentsconfigured to disengage a ground drive without disengaging a deck drive,allowing riding lawn mower 100 to operate a deck drive while remainingstationary and/or moving only under the influence of gravity (forexample, down a hill). In various prior lawn mowers, operation of thebypass required use of a hand, for example grasping the end of a leverand pulling. In contrast, riding lawn mower 100 is configured with afoot-operated bypass (for example, a bypass operated via a downwardforce applied by a foot), eliminating the need to bend over to operatethe bypass. In an exemplary embodiment, operation of the foot-operatedbypass of riding lawn mower 100 results in physical disengagement offlywheel 134 from friction wheel 140, preventing transfer of power todifferential 150 and thus preventing powered operation of ground drive160.

In an exemplary embodiment, riding lawn mower 100 is configured with aconstant load clutch. Many previous riding lawn mowers have beenconfigured with an “over center” clutch which rapidly engages the engineto components of the drivetrain. In contrast, in various exemplaryembodiments, riding lawn mower 100 utilizes a constant load clutchwherein engine 130 and deck drive 170 are gradually engaged over a rangeof angular motion of a clutch lever arm. In various exemplaryembodiments, the constant load clutch engages over a range of angularmotion of the clutch lever arm from about 15 degrees to about 40degrees. In an exemplary embodiment, the constant load clutch engagesover a range of angular motion of the clutch lever arm of about 25degrees. In this manner, load is placed on engine 130 in a gradualfashion, reducing the likelihood of engine 130 stalling. Thus, asmaller, less powerful, and/or less expensive engine 130 may be utilizedin riding lawn mower 100 as compared to prior riding lawn mowers.

In various exemplary embodiments, with momentary reference again to FIG.1A, riding lawn mower 100 is configured with a self-centering cuttingdeck 184. As used herein, “self-centering” generally refers to a cuttingdeck configured to return to a centered position with respect to thesides of lawn mower 100 after being displaced. For example, when anoperator steps on cutting deck 184, cutting deck 184 and/or componentscoupling cutting deck 184 to frame 210 are configured to flex, bend,slide, and/or otherwise move responsive to the applied force. Thus,cutting deck 184 may move sideways a certain distance. Once the appliedforce is removed, for example when an operator removes a foot, cuttingdeck 184 returns to a centered position. Self-centering may be achieved,for example, via suspending cutting deck 184 from frame 210 in asuitable manner, for example by utilizing angled metal bars havingsimilar dimensions. Responsive to displacement of cutting deck 184, thebars generate a force tending to move cutting deck 184 back to acentered position. Springs and other mechanical approaches may also beutilized, as suitable.

While the principles of this disclosure have been shown in variousembodiments, many modifications of structure, arrangements, proportions,the elements, materials and components, used in practice, which areparticularly adapted for a specific environment and operatingrequirements may be used without departing from the principles and scopeof this disclosure. These and other changes or modifications areintended to be included within the scope of the present disclosure andmay be expressed in the following claims.

The present disclosure has been described with reference to variousembodiments. However, one of ordinary skill in the art appreciates thatvarious modifications and changes can be made without departing from thescope of the present disclosure. Accordingly, the specification is to beregarded in an illustrative rather than a restrictive sense, and allsuch modifications are intended to be included within the scope of thepresent disclosure. Likewise, benefits, other advantages, and solutionsto problems have been described above with regard to variousembodiments. However, benefits, advantages, solutions to problems, andany element(s) that may cause any benefit, advantage, or solution tooccur or become more pronounced are not to be construed as a critical,required, or essential feature or element of any or all the claims. Asused herein, the terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. When language similar to “at least one of A, B, or C” or “atleast one of A, B, and C” is used in the claims or specification, thephrase is intended to mean any of the following: (1) at least one of A;(2) at least one of B; (3) at least one of C; (4) at least one of A andat least one of B; (5) at least one of B and at least one of C; (6) atleast one of A and at least one of C; or (7) at least one of A, at leastone of B, and at least one of C.

What is claimed is:
 1. A riding lawn mower comprising: a cutting deckhousing a cutting blade; an engine; a deck drive coupled to the engineto receive power for operating the cutting blade; a ground drive coupledto the engine to receive power for movement of the riding lawn mowerover ground; and a friction drive comprising a flywheel and a frictionwheel, wherein the flywheel couples the deck drive to the engine,wherein the flywheel comprises a neutral bearing system, wherein theflywheel is coupled to the ground drive via the friction wheel, whereinthe flywheel comprises a substantially disc shaped face disposed toengage at least a portion of the friction wheel to impart motion on thefriction wheel responsive to rotation of the flywheel when the flywheelcontacts the friction wheel, and wherein the neutral bearing system isdisposed proximate to an axis of rotation of the flywheel to preventfrictional engagement of the flywheel and the friction wheel at aportion of the flywheel that is covered by a cover plate of the neutralbearing system.
 2. The riding lawn mower of claim 1, wherein the axis ofrotation of the flywheel is substantially perpendicular to an axis ofrotation of the friction wheel.
 3. The riding lawn mower of claim 1,wherein an axis of rotation of the friction wheel is substantiallyparallel to a plane in which the disc shaped face lies, and wherein thefriction wheel transitions from transferring drive power for forwardmovement of the riding lawn mower to transferring drive power forreverse movement by moving linearly along the axis of rotation of thefriction wheel from a location proximate to one side of the face to alocation proximate to an opposite side of the face.
 4. The riding lawnmower of claim 1, wherein the neutral bearing system comprises the coverplate and a bearing configured to enable the cover plate to remainstationary while the flywheel rotates.
 5. The riding lawn mower of claim4, wherein the bearing comprises a needle bearing, a roller bearing, ora ball bearing.
 6. The riding lawn mower of claim 1, wherein thefriction wheel and the flywheel form a portion of a drivetrain of theriding lawn mower in combination with a differential, wherein thedifferential comprises at least one plastic gear, wherein thedifferential is coupled to the friction wheel in order to transfer powerto at least one drive wheel of the riding lawn mower.
 7. The riding lawnmower of claim 6, wherein translation of the friction wheel into areverse position with respect to the flywheel mechanically operates areverse detection sensor.
 8. The riding lawn mower of claim 1, whereinthe flywheel comprises powdered metal.
 9. The riding lawn mower of claim1, wherein the flywheel is configured to provide power to the grounddrive via engagement with the friction wheel, the flywheel engaging aportion of the friction wheel over at least two regions comprising: afirst region where the engagement between the flywheel and the frictionwheel causes movement of the riding lawn mower in a forward direction,and a second region where engagement between the flywheel and thefriction wheel causes movement of the riding lawn mower in a reversedirection.
 10. The riding lawn mower of claim 9, wherein the frictionwheel engages the neutral bearing system at a third region of theflywheel.
 11. The riding lawn mower of claim 10, wherein the thirdregion is disposed centrally between the first region and the secondregion.
 12. The riding lawn mower of claim 10, wherein the frictionwheel engages the flywheel in the first region at a portion of theflywheel that is displaced from the axis of rotation of the flywheel ina first direction, and wherein the friction wheel engages the flywheelin the second region at a portion of the flywheel that is displaced fromthe axis of rotation of the flywheel in a second direction that isopposite of the first direction.
 13. The riding lawn mower of claim 9,wherein an axis of rotation of the friction wheel is substantiallyparallel to a plane in which the disc shaped face lies, and wherein thefriction wheel transitions from transferring drive power in the forwarddirection to transferring drive power in the reverse direction by movinglinearly along the axis of rotation of the friction wheel from alocation proximate to one side of the face to a location proximate to anopposite side of the face.
 14. The riding lawn mower of claim 1, whereinthe engine is configured to have a displacement of less than about 225cubic centimeters.
 15. The riding lawn mower of claim 1, wherein theriding lawn mower weighs less than about 87 kilograms.
 16. The ridinglawn mower of claim 1, wherein the riding lawn mower has a wheelbase ofabout 112 centimeters.
 17. The riding lawn mower of claim 1, wherein theriding lawnmower weighs less than about 87 kilograms, wherein the engineis configured to have a displacement of less than about 225 cubiccentimeters, and wherein the riding lawn mower has a wheelbase of about112 centimeters.
 18. The riding lawn mower of claim 1, wherein theengine is configured to have a displacement of less than about 190 cubiccentimeters.
 19. The riding lawn mower of claim 1, further comprising aframe configured to support the engine, wherein the frame comprises atleast one curved portion configured to flex to provide an equivalent ofabout 2 centimeters of suspension travel.
 20. A friction drive for ariding lawn mower comprising a cutting deck housing a cutting blade, anengine, a deck drive coupled to the engine to receive power foroperating the cutting blade, and a ground drive coupled to the engine toreceive power for movement of the riding lawn mower over ground, thefriction drive comprising: a flywheel; and a friction wheel, wherein theflywheel couples the deck drive to the engine, wherein the flywheelcomprises a neutral bearing system, wherein the flywheel is coupled tothe ground drive via the friction wheel, wherein the flywheel comprisesa substantially disc shaped face disposed to engage at least a portionof the friction wheel to impart motion on the friction wheel responsiveto rotation of the flywheel when the flywheel contacts the frictionwheel, and wherein the neutral bearing system is disposed proximate toan axis of rotation of the flywheel to prevent frictional engagement ofthe flywheel and the friction wheel at a portion of the flywheel that iscovered by a cover plate of the neutral bearing system.